Potassium Channel Interacting Protein 2 (KChIP2) is not a transcriptional regulator of cardiac electrical remodeling

Sine V. Winther, Tomi Tuomainen, Rehannah Borup, Pasi Tavi, Gudrun Antoons, Morten B. Thomsen*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Web of Science)

Abstract

The heart-failure relevant Potassium Channel Interacting Protein 2 (KChIP2) augments Ca(V)1.2 and K(V)4.3. KChIP3 represses Ca(V)1.2 transcription in cardiomyocytes via interaction with regulatory DNA elements. Hence, we tested nuclear presence of KChIP2 and if KChIP2 translocates into the nucleus in a Ca2+ dependent manner. Cardiac biopsies from human heart-failure patients and healthy donor controls showed that nuclear KChIP2 abundance was significantly increased in heart failure; however, this was secondary to a large variation of total KChIP2 content. Administration of ouabain did not increase KChIP2 content in nuclear protein fractions in anesthetized mice. KChIP2 was expressed in cell lines, and Ca2+ ionophores were applied in a concentration- and time-dependent manner. The cell lines had KChIP2-immunoreactive protein in the nucleus in the absence of treatments to modulate intracellular Ca2+ concentration. Neither increasing nor decreasing intracellular Ca2+ concentrations caused translocation of KChIP2. Microarray analysis did not identify relief of transcriptional repression in murine KChIP2(-/-) heart samples. We conclude that although there is a baseline presence of KChIP2 in the nucleus both in vivo and in vitro, KChIP2 does not directly regulate transcriptional activity. Moreover, the nuclear transport of KChIP2 is not dependent on Ca2+. Thus, KChIP2 does not function as a conventional transcription factor in the heart.
Original languageEnglish
Article number28760
JournalScientific Reports
Volume6
DOIs
Publication statusPublished - 28 Jun 2016

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